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August 2014

Keep Home Canning Safe

Summer can be fleeting—its warm embrace lingering for too short a time. Canning is one way you can capture some of the season. The flavors of your garden can last well into winter and beyond. But make sure you do it right to prevent food poisoning.

Jar of green beans

A serious illness

More than 48 million cases of food poisoning happen every year. Unfortunately, many go unreported. From 1998 to 2008, most incidents were linked to food prepared in a restaurant. Only 9% of cases started in home kitchens.

Home canning accounts for many of the home-related food poisoning cases in the U.S. Not following proper safety methods while canning can put you and your family on contact with Clostridium botulinum. It’s a germ that lives in the soil. If it ends up in a can or jar, it can thrive and become toxic. Eating canned food that contains the germ can cause botulism.

Botulism is a serious illness. It attacks the nervous system. Even a small amount can be fatal. Signs of botulism include:

  • Double or blurred vision

  • Drooping eyelids

  • Slurred speech

  • Dry mouth

  • Muscle weakness

  • Difficulty swallowing or breathing

Canning safety tips

When done correctly, canning can preserve the nutritional quality of foods. The process sterilizes the food and protects it from the botulism germ. Canned foods can last months to years on a shelf. But once opened, they should be refrigerated.

To help ensure your canned goods are safe to eat, follow these steps:

  • Pick quality produce. Discard any fruits or vegetables that show signs of disease or decay. Can veggies within 12 hours after harvesting.

  • Choose the right equipment. For low-acid foods, such as green beans or carrots, use a pressure cooker or canner. It raises the temperature high enough—240 to 250° F (115.5 to 121° C) — to destroy harmful germs. For high-acid foods like tomatoes, you can use a boiling-water canner. These foods have a natural acidity that prevents germs from growing.

  • Know the time it takes to safely process your produce. How long you should cook food depends on many factors, including the type of fruit or vegetable you want to can. Altitude can also affect processing times. When using a pressure cooker, it’s also important to make sure the gauge is accurate. Always follow recommended cooking times from current and trusted recipe sources. The USDA offers an online canning guide.

  • Check canned food before you eat it. You can’t always tell if food is contaminated with botulism. Avoid eating it if the jar or can is bulging, cracked, or leaking. Confirm that the lid is still securely sealed before opening. Never taste canned goods that smell bad or look moldy or discolored. Discard canned items if the contents spurt out when you open the container. Wipe up any spills using a diluted bleach solution. Store canned goods in a cool, dry place, if possible.

  • Make sure your pressure canner is in good condition. Keep the vent ports on your pressure canner clean and free of any debris. If your canner is equipped with rubber gaskets, be sure that they are soft and flexible. Don't use the canner if the gasket is brittle, sticky, or cracked. Here is more information on the proper use of pressure canners. 


To learn more about botulism, take this quiz.


Online resources